A
number of artists have made proposals for creating monumental artworks
to be placed in Earth orbit which could be seen with unaided vision by
those on Earth. While there has been a variety of technologies suggested
most of the proposals have utilized some form of inflatable space technology.

The
idea of using inflatable structures goes back to the first Echo satellites
launched by the US in the 60's - although a number of inflatable concepts
for space applications pre-dated these satellites. These were passive
communication satellites and carried no other payload. However, they were
significant because, in addition to their scientific objectives, many
people actually saw these quite visible objects passing overhead in the
night sky.

Echo
1A
launched on August 12, 1960 was a sphere with a diameter of 30.5 meters
made out of metallic coated plastic film called Mylar which was 0.0127
mm thick and gave a total mass of 76 kg.

Echo
2 launched
in 1964 incorporated improvements in satellite surface fabrication and
overall shape, and featured a larger diameter of 41 meters and had a total
mass of 256 kg.

Echo-1A
and Echo-2 continued in orbit until 1968 and 1969, respectively. Reflected
light from the Echo satellites, essentially spherical "mirrors"
in orbit, was extremely bright and could be observed from a wide range
of points on Earth due to relatively high orbital altitude of 1,000-2,000
km. As a result, Echo-1 and -2 became well-known among sky-gazers as representative
artificial satellites of the 1960's.

Technological
Considerations

There
are several problems with the use of Mylar as a material for inflatable
objects in orbit. First, its hydrocarbon basis is attacked by oxygen atoms
in lower orbits and long exposure to UV light causes it to degrade becoming
brittle and opaque. So a new polyamide material called Kapton was developed
which had more resistance to this problem and Kapton has since been used
successfully. Most of the gold foil material you see on spacecraft and
satellites is usually Kapton.

Two
other problems affecting the use of inflatable structures in orbit are
atmospheric drag and the potential for meteorite penetration. To minimize
atmospheric drag one must select an orbit well above 300 km or the atmospheric
drag will immediately de-orbit the structure. Of course a higher orbit
has less atmospheric drag but in order for the sculpture to be visible,
a higher orbit also means a larger structure and this increases both the
manufacturing and launch costs.

Furthermore,
a "stiffer" object will be more stable and more resistant to
the effects of atmospheric drag. The advantages of "stiffness"
combined with a possible solution to the penetration problem by meteorites
and space debris led to the development of a new kind of inflatable space
technology and an exotic material referred to as "Inflatable Space
Rigidizable Structures" (ISRS) also called "Chemically Rigidizable
Expandable Membranes" ( CREM) structures.

This
ISRS material is a laminated sandwich of metallic coated Kapton and Kevlar
which has been impregnated with a UV sensitive resin . The material is
very lightweight and flexible permitting it to be easily folded and packaged.
Once it is inflated in space, it must "cure" in sunlight which
causes the resin to harden and the membrane to rigidize which stabilizes
the shape of the inflated object. In the late 80's and early 90's this
technology was under development at Contraves Space A.G. in Switzerland
which was funded by the European Space Agency. Recently, several companies
in Europe and in the U.S. have renewed their development of this type
of technology.

Orbital
Sculptures Using Inflatable Technology

In
the mid 80's several proposals for large orbital sculptures were made
that utilized some type of inflatable space technology.

In
1986 - the Eiffel Tower Corporation held a competition for an orbiting space
sculpture to celebrate its 100th anniversary. The winning entry was submitted
by a group of architects from Paris called "Groupe Spirale" led
by Jerome Gerber who proposed a large circular structure named: Anneau
de Lumiere or Ring of Light consisting of 100 Echo like
balloons connected to a thin tubular ring approximately 7.6 km in diameter.
Placed in a 700 km orbit this sculpture would appear to an observer on Earth
as a circle slightly larger than the Moon.

French
artist Pierre Comte was the second place finalist with his Arsat
a 45 m rectangular solar sail that would have created a bright artificial
star in the sky.

Dieter
Kassing proposed a 50 meter in diameter Space Disk with Morse
Code message. Also designed a bright blinking star in the sky.

Ultimately
the design Anneau de Lumiere proved to be too unstable to
maintain its shape in orbit and, as there was also much resistance from
the astronomers, the project to celebrate the Eiffel Tower Anniversary
with a visible orbital artwork was eventually canceled by the Eiffel Tower
Corporation.

For
the 1990 Goodwill Games, artist James Pridgeon proposed an orbital sculpture
called the "Goodwill Constellation" which connected several
inflatable spheres along a tether creating a precise line of lights in
the sky.

In
the mid 80's I proposed to celebrate the new millennium by placing "Circle
in the Sky "
which would be visible to the entire Earth's population as a symbol of
planetary unity and peace. I called this sculpture the Orbiting Unification
Ring Satellite or O.U.R.S. It was designed to be a global artwork including
participation by artists from all nations in the world in its development.
Thus the acronym "OURS" also stood for "belonging to us".

In
1986 I got into contact with Contraves Space A.G. in Switzerland and with
their chief engineer of inflatable technology development - Dr. Marco
C. Bernasconi - who later joined my project as vice president of the OURS
Foundation.

Subsequently,
to meet the requirements of space deployment and visibility we designed
the O.U.R.S. using ISRS technology to be a continuous torus with a diameter
of 1 km and a ring thickness of 10 meters. Placed at a 400 km orbit this
structure would be visible to viewers on Earth as a "Circle
in the Sky"
approximately 1/4 the size of Moon. With a magnitude of -7.28 the sculpture
would have been much brighter than the brightest star Sirius which has a
magnitude of -1.142, or Jupiter -2.0 or Venus -4.4.

The
ISRS material that was available at that time had an area/mass ratio of
0.2 kg/m2 resulting in a total launch mass of approximately 19,739 kg.
Such a structure would require the total payload capacity of an Ariane
5 or Titan 4 launcher. Since then, advances in CREM materials have reduced
the mass of such a sculpture by approximately 35% and, while the mass
is less, the volume of the packaged sculpture would still require most
of the payload volume of either of these launchers.

In
the development of the O.U.R.S. project we planned to fly a smaller "prototype"
version of the sculpture in order to test both the concept and the technology.
Contraves Space A.G. had developed a six-meter ISRS torus for testing purposes.
As most of the technical design work had already been done I proposed to
Contraves to build a similar structure for our prototype project which was
called the "OUR-Space
Peace Sculpture".
This sculpture was circle divided by a central cross - a symbolic form which
was the astronomical symbol of the Earth and an ancient symbol found in
many cultures .

As
the Cold War was still going on and "space" was seen as a great
environment for international cooperation, the idea was to launch the sculpture
to the Mir space station and have a cosmonaut deploy it during a space walk
with the deployment being transmitted by video to Earth.

In
1988, I signed a preliminary agreement with the Soviet space officials at
Glavkosmos for the space flight of the sculpture. However, due to some technological
uncertainties, Contraves turned out to be very slow in committing to the
project and the Soviets had their own inflatable technology which they promoted
very strongly.

The
material they were using was a type of thick space rubber that required
permanent pressurization. In 1984, they had successfully flown two 20 m
diameter inflatable antennae on a Progress vehicle shown above. The Russian
engineers said they were also developing a rigidizable inflatable technology
as well.

Subsequently,
in 1990 NPO Energia, built and delivered to the OURS Foundation a full size
mock-up of the sculpture which we were able to inflate and display to space
and art communities on several occasions.

Our
target date for the deployment of the OUR-SPS was in 1992 to celebrate
the International Space Year. To make a long story short, the dissolution
of the Soviet Union resulted in many uncertainties in that time frame
which affected sponsor support for the project. In the end the project
had to be postponed.

However,
this development and the connections established with the Russian space
program led to the spaceflight of my Cosmic Dancer Sculpture on the Mir
station just one year later in 1993.

In
the meantime, the idea of the launching the O.U.R.S. did not die. Some
years ago, before anyone knew it was going to be filmed, the producers
of "Lord of the Rings" contacted the OURS Foundation to see
if I was still working on the O.U.R.S. project and that they might be
interested in putting a "ring" in the sky to announce their
new film. However, it was quickly realized that the costs of an Ariane
5 and the costs of manufacturing such a sculpture in a such short time
was not possible.

Recently,
there has been renewed interest in the space community for inflatable and
rigidizable space structures. The OURS Foundation was asked to re-examine
the O.U.R.S
concept and to suggest feasible alternative designs to the continuous torus
concept. This study, which was completed in September 2003, looked at several
new designs for inflatable sculptures that would create a visible "circle
in the sky" and have a mass in the vicinity of 4,000 kg. One of these
designs is shown above.

As
the "new space age" begins in ernest, the demand for inflatable
space technology will increase. Solar Sail missions launched from Earth
orbit to destinations throughout the Solar System, orbiting Solar Power
Satellites supplying terrestrial civilization with the necessary clean
energy and maybe even visible art works may become the "signs of
the times" in the sky as all of these may rely on inflatable structures.